Shino died of starvation on the island being separated from her friendat she fell down underground of the Island and survived for a while thus she died.

Satomi then bring her soul to his realm and offered her to live in his new world. But first,she had to follow him to get Emilia & Satella's fusion medal that is sealed in their different timelines via time travelling

Then Shino agreed to live in Satomi's world as she is recruited the position at his school as the President of Student Council.